A Guide to Modern Koi Pond Construction
Vortex chamber by-pass
![[Vortex chamber]](img/vort.gif)
In normal pond operation A & D are open, and B & C are shut. When you wish to purge the bottom drain, then A is closed, and C is open. The pipe from C can be 3"or 4" diam. In the case of the very large vortex chambers the drain pipe is 3" diam so in that case the two drain pipes could be connected.
![[Vortex chamber]](img/fit1.gif)
This photograph shows a system similar to
the one in the sketch above, and was photographed on a pond in the north
of England.
The inlet from the bottom drain is on the left of the photo
and is fitted with a slide valve. This valve (D) is not used, and is
only fitted in case there is a failure of one of the other valves. The
vortex chamber can be seen on the right of the photo, and the inlet valve
(A) is in fact a double union ball valve. Below the tee-piece is another
double union ball valve (C), and this is connected to an open ended pipe
which allows you to discharge the water to the drains box. The valves
in the lower part of the photo are the drain valves from the vortex chamber
and the filters. The double union ball valves are far superior to the
slide valves, but are more expensive especially when you require them
for four inch pipe and above.
Some koi-keepers use them for 1½"or 2"pipework,
but it is generally accepted that due to cost then the slide valves can
be used for the 4"pipework as if you use the system on Purging
the drains then the water cannot be lost even if the slide valve fails.
We will now continue with the pipework for mid-water suction.
This website started with a booklet which I made up originally for the help of those members of the BKKS - South Wales Section who were intending to start building a koi pond, and as the website has expanded more information and articles from other people have been included. This is for general guidance only, and we do not take any responsibility for problems that might occur by following these ideas. It is important that you check out everything in your area, and check on local laws and rules that may apply.